<?php
/**
 * @package library
 */

/**
 * 验证码类
 * 
 * @package library
 * @author zqy
 * @version 1.0
 */
class Captcha {
    
    private $charset = 'abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789';//随机因子  
    private $code;//验证码  
    private $codelen = 4;//验证码长度  
    private $width = 130;//宽度  
    private $height = 50;//高度  
    private $img;//图形资源句柄  
    private $font;//指定的字体  
    private $fontsize = 20;//指定字体大小  
    private $fontcolor;//指定字体颜色  

    //构造方法初始化  
    public function __construct() {  
        $this->font = dirname(__FILE__).'/font/elephant.ttf';//注意字体路径要写对，否则显示不了图片  
    }  

    //生成随机码  
    private function createCode() {  
        $_len = strlen($this->charset)-1;  
        for ($i=0;$i<$this->codelen;$i++) {  
            $this->code .= $this->charset[mt_rand(0,$_len)];  
        }  
    }  
    
    //生成背景  
    private function createBg() {  
        $this->img = imagecreatetruecolor($this->width, $this->height);  
        $color = imagecolorallocate($this->img, mt_rand(157,255), mt_rand(157,255), mt_rand(157,255));  
        imagefilledrectangle($this->img,0,$this->height,$this->width,0,$color);  
    }  
    
    //生成文字  
    private function createFont() {  
        $_x = $this->width / $this->codelen;  
        for ($i=0;$i<$this->codelen;$i++) {  
            $this->fontcolor = imagecolorallocate($this->img,mt_rand(0,156),mt_rand(0,156),mt_rand(0,156));  
            imagettftext($this->img,$this->fontsize,mt_rand(-30,30),$_x*$i+mt_rand(1,5),$this->height / 1.4,$this->fontcolor,$this->font,$this->code[$i]);  
        }  
    }  
    
    //生成线条、雪花  
    private function createLine() {  
        //线条  
        for ($i=0;$i<6;$i++) {  
            $color = imagecolorallocate($this->img,mt_rand(0,156),mt_rand(0,156),mt_rand(0,156));  
            imageline($this->img,mt_rand(0,$this->width),mt_rand(0,$this->height),mt_rand(0,$this->width),mt_rand(0,$this->height),$color);  
        }  
        //雪花  
        for ($i=0;$i<100;$i++) {  
            $color = imagecolorallocate($this->img,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255));  
            imagestring($this->img,mt_rand(1,5),mt_rand(0,$this->width),mt_rand(0,$this->height),'*',$color);  
        }  
    }
    
    //输出  
    private function outPut() {  
        header('Content-type:image/png');  
        imagepng($this->img);  
        imagedestroy($this->img);  
    }  
    
    //对外生成  
    public function doImg() {  
        $this->createBg();  
        $this->createCode();  
        $this->createLine();  
        $this->createFont();  
        $this->outPut();  
    }  
    
    //获取验证码  
    public function getCode() {  
        return strtolower($this->code);  
    }  
}
?>